The Pozzi sale of April 1921 is one of the highlights of 20th century numismatic catalogues. The sale, catalogued by Jacob Hirsch and held at Naville & Cie. took place on Apr 4, 1921 andcontained 3334 lots of Greek coins fully illustrated on 101 plates (I have an unplated copy of the catalogue). The catalogue is further described in Spring, Ancient Coin Auction Catalogues1880-1980, pp. 174-175.

The Wall Street Journal (Feb. 15-16, 2020) contains a striking portrait of the collector, Samuel Jean Pozzi, "Dr. Pozzi at Home" (1881) by the painter John Singer Sargent, wearing a red(scarlet) robe (reminiscent of Baroque paintings of Popes and Cardinals). This was 40 years before the sale. The illustration accompanies a book review of Julian Barnes' book "The Man in the RedCoat" by Sue Roe. I have read the review but not the book, which is just out.

There is in fact no specific mention in the article of Pozzi's collecting interests, but rather of his medical achievements, celebrity and celebrity associates as a "man about town", andcontradictory character. He was a pioneering gynecologist when the specialty was coming to be separate from general medicine, and the President of France was present at the opening of his modernizedhospital in 1899. He emphasized care and consideration for the patient. His friends and associates included Oscar Wilde, Sarah Bernhardt, and a host of Proustian aristocrats. While the reviewerstates "no spoilers" about how Pozzi died, that is well covered in Spring, page 175.

To read the complete WSJ article (subscription required), see:
'The Man in the Red Coat' Review: The Toast of Belle Époque Paris(https://www.wsj.com/articles/the-man-in-the-red-coat-review-the-toast-of-belle-epoque-paris-11581695454)